Hollow-fibre polyester

Hollow-fibre polyester (hollow fibre, HCS = hollow conjugated siliconized) is a spun polyester staple fibre with one or more hollow channels in its cross-section. The cavities are formed during extrusion by special spinnerets with C-, cross- or four-channel geometry. Effect: the fibre weighs up to 30 percent less at the same outer contour, traps still air and provides strong insulation. Typical deniers are 3-15, fibre lengths 32 to 64 mm.

Key applications are wadding (quilted jackets, winter parkas), fillings for cushions, pillows and duvets, and bedding stuffings (bedding to DIN EN 12934). Siliconised (S) fibres are extremely soft, hardly clump and are machine washable. HCS is also used in lightweight fleece fabrics to boost hand feel and thermal performance without adding weight.

Advantages over down: no animal product, hypoallergenic, washable at 60 degrees, insulates even when wet. Brands like 3M Thinsulate, Coreloft (Arc'teryx), Climashield and Toray Airfibre use HCS constructions specifically for ski wear, softshells and mountaineering jackets. Recycled versions from PET bottle flakes (rPET-hollow) are now standard - GRS-certified material is available without price premium.